The separation of a solid phase from a liquid phase in a solid-liquid mixture is a challenging task that is relevant to many industries including wastewater, drinking water, pharmaceutical, chemical, food, agriculture, and mining. Thorough and efficient solid-liquid separation is essential, especially considering the high cost of solids disposal for many industries. Solid-liquid separation can be achieved by chemical or physical processes or, more typically, a combination of both. In many applications, the solid-liquid separation process involves pretreatment, solids concentration, solids separation, and post-treatment. Generally, solid-liquid separation is achieved by two different separation methods, namely sedimentation or filtration. Sedimentation techniques rely on the different densities of the solid and liquid phases to accomplish separation. Principally, sedimentation techniques include gravity, centrifugal, electrostatic, and magnetic. On the other hand, filtration methods involve a medium, e.g., a screen or membrane, which retains the solid phase while allowing the liquid phase to pass through the medium. Filtration can be achieved by pressure, vacuum, centrifugal, or gravity operations.
Chemical pretreatment is used to enhance separation of the solid and liquid phases through coagulation or flocculation. However, the addition of chemicals may reduce the suitability of the separated solid phase for land application. For example, many sedimentation systems utilize gravity because this process is relatively simple and inexpensive. However, the operation of gravity alone leads to extremely long settling times. Therefore, chemical pretreatment is necessary to coagulate solids and increase the rate of sedimentation. Unfortunately, the addition of chemicals can reduce the usefulness and desirability of the separated solid phase for land application or other beneficial reuses.
Furthermore, cost effective solid-liquid separation technologies are essential for economical separation of the solid and liquid phases. These technologies are required to operate reliably while providing low installation, operating, and maintenance costs. Nevertheless, many technologies do not satisfy these requirements and instead demand high operating and maintenance costs.
In animal agriculture, producers seek alternative treatments and processing technologies for liquid manure to reduce excessive nutrient loading and odor potential of liquid manure storage structures. Liquid manure systems are popular with livestock operations because the manure is easier to handle, store, and biologically treat. Furthermore, the manure pits and gutters are also easy to recharge and flush using lagoon liquid.
Solid-liquid separation of liquid manure results in liquids that are easier to pump and handle. Additionally, the process helps to reduce the amount of organic material in treatment lagoons, odors in storage and treatment facilities, solids build-up in primary lagoons, frequency of lagoon sludge removal, and potential surface water and groundwater pollution. Beneficial uses of the recovered solids include bedding materials, animal feed supplements, composts, and soil amendments.
Known methods and devices for solid-liquid separation of animal manure are laborious and inefficient, with high operating costs. Furthermore, demands for product purity and environmental acceptability of waste materials necessitate solid-liquid separation techniques that can meet these requirements. Therefore, a need exists to provide an easy to operate and efficient solid-liquid separator for separating solids from liquids in a solid-liquid mixture. This solid-liquid separator would also enable the operator to easily adjust the machine according to the solids content of the solid-liquid mixture. A need further remains for a solid-liquid separator of simple construction particularly adapted for processing manure and other types of wastes.